from bs4 import BeautifulSoup
html_doc = """
<html><head><title>The Dormouse's story</title></head>
<body>
<p class="story"><!--fssfsffda..sdfafaff--></p>
<p class="title"><b>The Dormouse's story</b></p>
<p class="story">Once upon a time there were three little sisters; and their names were
<a href="http://example.com/elsie" class="sister" id="link1">Elsie</a>,
<a href="http://example.com/lacie" class="sister" id="link2">Lacie</a> and
<a href="http://example.com/tillie" class="sister" id="link3">Tillie</a>;
and they lived at the bottom of a well.</p>
<p class="story">...</p>
"""
#1.转换类型
soup=BeautifulSoup(html_doc,'lxml')
print(type(soup))#<class 'bs4.BeautifulSoup'>
#2.格式化输出(补全)
result=soup.prettify()
print(result)

result=soup.head
print(result)
#四大属性:Tag, NavigableString, BeautifulSoup, and Comment.
#标签对象 Tag
result=soup.p#.(点)只能取到第一个数据(标签对象)
print(result)
#Navigablestring
result=soup.a.string#取文本
print(result)

result=soup.a['href']#取属性
print(result)

#comment 注释
result=soup.p.string
print(type(result))#<class 'bs4.element.Comment'>
print(result)